The present invention relates to an improvement in a four-way valve for a reversible refrigeration cycle.
The applicant has proposed a four-way valve for a reversible refrigeration cycle of the type which has a plunger or piston and annular valve tongues or walls moulded integrally to constitute a valve spool. The present invention constitutes an improvement to such a prior art concerning the switching mechanism for operating the valve spool.
A four-way valve of the type described comprises a casing constituted by two cylinders of different diameters connected together. Open into the casing are a delivery tube which leads to the delivery side of a compressor, a suction tube leading to the suction side of the compressor, and tubes leading to first and second heat exchangers, respectively. A valve member is slidably disposed in the casing to selectively communicate the suction tube with the two tubes leading to the heat exchangers. The valve member is actuated by mechanism which includes a solenoid operated two-way valve. The valve member comprises a unitary valve spool having a hollow cylindrical section around which first to third pressure receiving portions are formed; the first and second pressure receiving portions sliding in a larger diameter cylinder of the casing and the third pressure receiving portion sliding in a smaller diameter cylinder of the same casing, both within a range of selective communication between the suction tube and the two tubes connected with the heat exchangers. An opening is formed through the peripheral wall of the hollow cylindrical section between the first and second pressure receiving portions. The suction tube is selectively communicatable with the tubes concerned depending on the positional relationship between the three pressure receiving portions and the casing, which varies with the movement of the valve spool.